My router only has four downstream ports, and due to the layout of my house I only want to run one cable from the router to my home office anyway. If it had enough ports and the house was laid out differently I wouldn’t have bothered with the switch.

Unmanaged switches are usually quite a bit cheaper and just work. You plug everything in and that’s it. Managed switches need configuring and cost more. I paid $25 for my 8 port 10/100/1000 switch, while the managed version is about $120. With a managed switch you can do things like turn individual ports on and off, traffic limit and monitor per port, and other fancy networking things that I’ve never bothered with.